Electrolysis of water has been one of the most promising approaches for renewable energy resources while the efficient oxygen evolution reaction (OER) remains challenging. Herein, a series of different ratio of Se doped Co3O4 nanoparticles XSe-Co3O4 are prepared by hydrothermal method and applied as OER electrocatalysts. Se2− is doped into the Co3O4 crystal lattice by substituting of O2− and a large number of oxygen vacancies are generated, which provides more available activity sites for OER. Se doping increases the surface ratio of Co2+/Co3+ and accelerates the electron transport that favors OER activity promotion. The optimized doping ratio of 6%Se–Co3O4 presents low overpotential of 281 mV at 10 mA cm−2, as well as a low Tafel slope of 70 mV dec−1 in 1 M KOH solution, which has great advantages compared to the recently reported Co3O4-based OER electrocatalysts. This work provides new ideas for the development of efficient Co3O4-based OER electrocatalysts. Display omitted •Se2− was doped into the Co3O4 and oxygen vacancies were generated.•Se doping increases the ratio of Co2+/Co3+ and accelerates electron transport.•Se doped with Co3O4 increases the charge transfer efficiency in the OER process.•The 6%Se–Co3O4 presents high OER activity with 281 mV@10 mA cm−2.